Cigarette filter and filter-tipped cigarette

ABSTRACT

A cigarette filter includes two or more filter sections of the following filter sections a filter section added with a liquid fatty acid ester or a liquid fatty acid having a viscosity of 1 to 300 cP, a filter section added with a glycol having a viscosity of 1 to 300 cP, and a filter section added with a charcoal.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This is a Continuation Application of PCT Application No. PCT/JP02/10989, filed Oct. 23, 2002, which was not published under PCT Article 21(2) in English.

[0002] This application is based upon and claims the benefit of priority from prior Japanese Patent Application No. 2001-332651, filed Oct. 30, 2001, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

[0003] 1. Field of the Invention

[0004] The present invention relates to a cigarette filter and a filter-tipped cigarette, and more specifically, to a cigarette filter that can efficiently filter the tobacco mainstream smoke when the cigarette is smoked, improving the tobacco taste, as well as a cigarette having such a filter.

[0005] 2. Description of the Related Art

[0006] Recently, an additive is added to cigarette filters for the purpose of improving the efficiency of filtration for the mainstream smoke from tobacco or improving the tobacco taste. Especially, a cigarette filter in which activated carbon (charcoal) is added to filter fibers makes up more than a half of the filters for the filter-tipped cigarettes in the Japanese market. On the other hand, there are regions of the world where it is customary that smoking is conducted by passing the tobacco smoke through water. However, when the tobacco smoke is filtered with water, its taste changes. So, Jpn. Pat. Appln. KOKAI Publication No. 63-276474 discloses an example in which water is added to a cigarette filter. Further, Jpn. Pat. Appln. KOKOKU Publication No. 44-29317 discloses a tobacco filter prepared by adding specified amounts of charcoal and polyalkylene glycol to a cellulose acetate fiber tow. Jpn. Pat. Appln. KOKOKU Publication No. 46-12957 discloses a tobacco filter prepared by adding various oils/fats and a sorbitan derivative to a filter material.

[0007] However, although the effect of the additive to the tobacco filter on the taste of the tobacco can be organoleptically detected in some cases, the most of the additives mentioned above are not used in tobacco filters that are presently available, since the filtration efficiency for each component of the tobacco mainstream smoke has not been scientifically clarified. As the tobacco filters, filters prepared by adding charcoal, which is said to eliminate the vapor components other than permanent gas by a great number of fine pores, to fibers, and filters made of acetate fibers or paper without addition of charcoal, only, are employed for commercially available tobaccos.

[0008] The addition of charcoal is effective means to increase the filtration efficiency for the vapor phase components of the tobacco mainstream smoke. However, in an initial stage of smoking, the fine pores of charcoal are clogged with tar contained in the tobacco mainstream smoke, and the charcoal loses its absorption activity. Thus, the filtration efficiency for the vapor phase components in the mainstream smoke while one cigarette is smoked decreases with time from the initial stage of the smoking to the final stage. However, if a large amount of charcoal is added to the filter in order to avoid the above-described drawback, the taste of the tobacco is degraded by the smell of the charcoal. Further, such measures are economically disadvantageous.

[0009] Therefore, an object of the present invention is to provide a cigarette filter that can efficiently filtrate the tobacco mainstream smoke for each component of the smoke.

BRIEF SUMMARY OF THE INVENTION

[0010] In an attempt to achieve the above-described object, the inventors of the present invention have carried out intensive studies in which cigarettes were manufactured using filters to which various additives were added respectively, and the mainstream smoke of each cigarette was analyzed before and after passing the filter. From the results, it has been found that the filtrated components of the tobacco mainstream smoke were significantly different from one cigarette to another depending on the type of additive used. Upon systematically reviewing the results, it has been found that filters added with liquid fatty acids having a low viscosity, i.e., a viscosity of 1 to 300 cP (e.g., lauric acid, oleic acid, linoleic acid and linolenic acid) are effective for the filtration of the entire tobacco mainstream smoke, that filters added with liquid fatty acid esters having a low viscosity, i.e., a viscosity of 1 to 300 cP (e.g., natural fats/oils such as olive oil, castor oil, rapeseed oil, corn oil, safflower oil and grape seed oil) are effective for the filtration of the low polarity components of the tobacco mainstream smoke, and hard to effectively filter the high polarity components, and that filters added with glycols having a low viscosity, i.e., a viscosity of 1 to 300 cP (such as polyethyleneglycol and propyleneglycol) are effective for the filtration of the high polarity components of the tobacco mainstream smoke, and hard to effectively filter the low polarity components. It has been further found that the vapor pressure of the components in the tobacco mainstream smoke that are absorbed by these additives is 1 to 4000 Pa, whereas the vapor pressure of the components in the tobacco mainstream smoke that are adsorbed by charcoal is 100 to 100,000 Pa, thus indicating a significant difference between the former and the latter.

[0011] Further, it has been found that if a fatty acid or a fatty acid ester and a glycol are added to the same filter, the filtration efficiency for the mainstream smoke is not improved, and the filtration effect is unstable. On the other hand, if a fatty acid, a fatty acid ester and glycol are mixed with charcoal and added to the same filter, the filtration efficiency for the mainstream smoke is lowered because the additives are attached to charcoal.

[0012] Then, in the present invention, the tobacco filter is divided into two or more sections and different types of additives (mainstream smoke component-removing agents) are added to respective sections. With this structure, each component of the tobacco mainstream smoke is filtrated by each respective section of the filter, thereby achieving a highly efficient mainstream smoke filtration.

[0013] Thus, according to the present invention, there is provided a cigarette filter comprising two or more filter sections of the following three filter sections (A) to (C):

[0014] (A) a filter section added with a liquid fatty acid ester or a liquid fatty acid, having a viscosity of 1 to 300 cP;

[0015] (B) a filter section added with a glycol having a viscosity of 1 to 300 cP is; and

[0016] (C) a filter section added with a charcoal.

[0017] In the case where the cigarette filter of the present invention comprises the filter section (A), the use of olive oil as the additive improves the flavor of the tobacco smoke, which is preferable. In the case where the cigarette filter of the present invention comprises the filter section (B), the use of propylene glycol as the glycol improves the filtration efficiency for, especially, the high polarity components in the tobacco mainstream smoke.

[0018] In the case where the cigarette filter of the present invention comprises the filter section (C), it is preferable that the filter section (C) be provided on a downstream side of the filter section (A). and/or filter section (B).

[0019] The cigarette filter of the present invention may include a plain filter section at the most downstream position.

[0020] According to the present invention, there is further provided a cigarette having a filter of the present invention provided at one end of a tobacco rod.

[0021] In the present invention, the upstream and downstream are based on the flowing direction of the mainstream smoke when the cigarette is smoked. In other words, the tobacco rod side is an upstream side and the mouthend side is a downstream side.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

[0022] The appended FIGURE is a partially developed perspective view of a filter-tipped cigarette according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0023] The present invention will now be described below in further detail.

[0024] The appended FIGURE is a partially developed perspective view of a filter-tipped cigarette according to an embodiment of the present invention. The FIGURE should be interpreted as also showing a cigarette filter according to an embodiment of the present invention.

[0025] A filter-tipped cigarette 10 shown in the FIGURE comprises a tobacco rod 20 including an ordinary tobacco filler material 201 such as cut tobacco and a tobacco wrapper paper sheet 202, and a filter 30 attached to an end of the tobacco rod 20. The structure of the portion other than the filter portion is similar to that of an ordinary filter-tipped cigarette. Therefore, an ordinary tobacco rod can be employed as the tobacco rod 20.

[0026] In the present invention, the filter comprises two or more filter sections of the following filter sections: (A) a filter section added with a liquid fatty acid ester or a liquid fatty acid, having a viscosity of 1 to 300 cP as a mainstream smoke component-removing agent; (B) a filter section added with a glycol having a viscosity of 1 to 300 cP as a mainstream smoke component-removing agent; and (C) a filter section added with a charcoal as a mainstream smoke component-removing agent.

[0027] Examples of the liquid fatty acid ester added to the filter section (A) are natural fats/oils such as olive oil, castor oil, rapeseed oil, corn oil, safflower oil and grape seed oil. Examples of the liquid fatty acid added to the filter section (A) are lauric acid, oleic acid, linoleic acid and linolenic acid. A preferable example of the mainstream smoke component-removing agent added to the filter section (A) is olive oil. The flavor of olive oil matches well with the flavor of tobacco. The amount of liquid fatty acid ester or fatty acid added is preferably 5% to 30% of the weight of the filter fibers.

[0028] Examples of glycols having a viscosity of 1 cP to 300 cP added to the filter section (B) are polyethylene glycol and propylene glycol. Of these, propylene glycol is preferable. The amount of glycol added is preferably 5% to 30% of the weight of the filter fibers.

[0029] An example of the charcoal added to the filter section (C) is charcoal used for an ordinary so-called charcoal filter, such as coconut shell charcoal. The amount of charcoal added is preferably 10 to 80 mg per 10 mm length of filter (circumference of filter 16.8 mm to 25.8 mm).

[0030] In the FIGURE, the filter 30 includes, e.g., four discrete filter sections, that is, from the upstream side, a first filter section 301, a second filter section 302, a third filter section 303 and a fourth filter section 304.

[0031] In a preferred embodiment of the present invention, the first filter section 301 provided in contact with the tobacco rod 20 is constituted by the above-described filter section (A), the second filter section 302 is constituted by the above-described filter section (B), and the third filter section 303 is constituted by the above-described filter section (C). The fourth filter section 304 located at the most downstream side is constituted by a plain filter intended to prevent the falling off of the charcoal in the third filter section 303 constituted by the above-described filter section (C). The plain filter does not contain any additive to remove the mainstream smoke, and it is made of substantially a filter material.

[0032] Each of the first to the fourth filter sections 301 to 304 is formed from a filter material used in ordinary cigarette filters, for example, paper, or a tow of synthetic fibers such as cellulose rayon fibers, cellulose acetate fibers or vinylon fibers. To these filter sections except for the fourth filter section 304, the mainstream smoke component-removing agents are added respectively. The mainstream smoke component-removing agents for the filter sections 301 and 302 can be added thereto by spraying or coating them to the respective filter materials. The charcoal used in the third filter section can be added thereto by dispersedly mixing it into the filter material by an ordinary method.

[0033] Needless to say, any one of the filter sections 301 to 303 can be omitted from the structure of the filter according to the preferred embodiment. Further, the filter section 304 can be omitted as well. However, the cigarette filter of the present invention most preferably has the filter section (C) on the downstream side of the filter sections (A) and/or (B). With this stricture, the filtration efficiency is improved in a synergetic manner. Further, when the filter section (C) is placed on the downstream side, the decrease with time in the filtration efficiency of the charcoal for the tobacco mainstream smoke can be suppressed.

[0034] It should be noted that each of the first to the fourth filter sections 301 to 304 is individually wrapped with a respective filter wrapper paper sheet (not shown) as required, and then they are wrapped with one wrapper paper sheet 310 to integrate them together. The thus formed filter 30 is attached to one end of the tobacco rod 20 by an ordinary tipping paper 320.

[0035] The present invention will now be described by way of Examples; however, the invention should not be limited to these Examples.

EXAMPLE 1

[0036] In order to confirm the influence of the polarity of the mainstream smoke component-removing agent, the filtration efficiency for the mainstream smoke components was evaluated for each of cigarette filters to which olive oil, propylene glycol and linoleic acid (each available from Wako Pure Chemical Industries, Ltd.) were added respectively as the mainstream smoke component-removing agent.

[0037] As the cigarette filter, a plasticizer-free cellulose acetate filter (3Y/43000) was used for each case. In each case, the mainstream smoke component-removing agent was sprayed in the form of fine particles onto the cigarette filter in amount of 35 mg, using an atomizer. As the tobacco rod, that of Mild Seven Super Light available from Japan Tobacco Inc. was used. For each case, the filter added with the respective mainstream smoke component-removing agent was attached to the tobacco rod with an adhesive tape, providing a sample cigarette.

[0038] Each sample cigarette was statically burned 15 mm, and then it was subjected to one puff under the standard smoking conditions. The mainstream smoke component flowing out of the filter was measured by a gas chromatography/mass spectrum analysis. The filtration efficiency for each mainstream smoke component was calculated as a ratio of the amount of the mainstream smoke component reduced with respect to the amount of the component measured with the tobacco rod without a filter. The results are shown in TABLE 1 below. TABLE 1 also lists the results obtained when a filter with no mainstream smoke component-removing agent added was used (control).

[0039] TABLE 1: Filtration efficiency for mainstream smoke components by various mainstream smoke component-removing agent TABLE 1 Filtration efficiency for mainstream smoke components by various mainstream smoke component-removing agent Components Mainstream smoke of component-removing agent Mainstream Olive Propylene Linoleic Smoke None Oil glycol Acid Hydrocarbons 32.9% 99.9% 65.3% 99.9% Pyridines 55.7% 98.7% 99.4% 99.8% Organic 57.0% 78.9% 87.8% 88.9% Acids Phenols 65.5% 96.2% 96.5% 94.7%

[0040] As presented in TABLE 1, in the case where olive oil was added, the filtration efficiency for hydrocarbons, pyridines and phenols were remarkably increased as compared to the case of the control filter. When propylene glycol was added, the filtration efficiency for pyridines, organic acids and phenols were remarkably increased, indicating different removing characteristics from those of the case of olive oil. When linoleic acid was added, excellent filtration efficiency was obtained for any of the mainstream smoke components indicated here. From these results, it can be seen that a mainstream smoke component-removing agent removes a mainstream smoke component having a polarity close to that of the removing agent preferentially to others.

EXAMPLE 2

[0041] In this Example, the effect of a combination of a filter section added with charcoal as a mainstream smoke component-removing agent and a filter section added with another mainstream smoke component-removing agent was evaluated.

[0042] (1) First, in order to evaluate the filtration efficiency-of-the charcoal-added filter alone, a sample filter section (charcoal filter) was prepared, which was added with charcoal used for ordinary cigarettes in an amount of 30 mg in the form of a filling layer (having a thickness of 2 mm). To prevent the charcoal from falling off from the layer, a plain cellulose acetate filter section (3Y/43000) having a length of 5 mm was placed on a downstream side of the charcoal filter section. This filter was attached to one end of a tobacco rod similar to that of Example 1. The obtained sample was compared with the same sample except that no charcoal was added, in terms of each mainstream smoke component, and the filtration efficiency was evaluated by an indirect method. The analyzing method employed was the same as in Example 1.

[0043] (2) In order to evaluate the filtration efficiency of an olive oil-added filter section alone, a filter section was prepared by adding 15 mg of olive oil to a cellulose acetate filter (3Y/43000) having a length of 20 mm by the same method as in Example 1. Then, the filtration efficiency for the mainstream smoke component was evaluated similarly.

[0044] (3) Next, the filter prepared in (1) above was placed on the downstream side of the olive oil-added filter section such that the charcoal filter section was disposed in contact with the olive oil-added filter section. The obtained filter was attached to a tobacco rod, and the filtration efficiency for the mainstream smoke component was evaluated similarly.

[0045] The results obtained are shown in TABLE 2 below. TABLE 2 Comparison in filtration efficiency (%) between single use of filter section and combined use of filter sections Components Filter Section of Single Combination Mainstream Charcoal Olive oil (Charcoal + Olive oil) Smoke added added Calculated Found Acetaldehyde 63.6 24.5 72.5 79.6 Benzene 70.9 38.8 82.2 95.7 Pyridine 57.1 83.1 92.7 98.1 Acetic acid 25.3 73.1 79.9 81.6 Phenol 3.7 89.5 89.9 94.0 Nicotine 7.6 65.4 68.0 67.0 Glycerol 0.0 61.1 61.1 61.0

[0046] In TABLE 2, the calculated value for the combination of the charcoal filter section with the olive oil-added filter section is a simply calculated value based on each of the filter sections used singly. As can be seen from TABLE 2, the comparison between the calculated values and the found values indicates that the filtration efficiency does not show a significant difference for the high boiling point components, but is significantly higher in the found values for the low boiling point components. From the results, it is seen that when a filter section added with charcoal as a mainstream smoke component-removing agent is combined, on the downstream side, with another filter section added with another mainstream smoke component-removing agent, a more excellent effect (synergetic effect) can be obtained as compared to the total effects obtained when the filter sections are used singly.

[0047] As described above, according to the present invention, there is provided a cigarette filter that can efficiently filtrate the tobacco mainstream smoke for each component thereof, and a filter-tipped cigarette comprising such a filter. 

What is claimed is:
 1. A cigarette filter comprising two or more filter sections of the following three filter sections (A) to (C): (A) a filter section added with a liquid fatty acid ester or a liquid fatty acid, having a viscosity of 1 to 300 cP; (B) a filter section added with a glycol having a viscosity of 1 to 300 cP is; and (C) a filter section added with a charcoal.
 2. The filter according to claim 1, wherein the fatty acid ester is olive oil.
 3. The filter according to claim 1, wherein the glycol is propylene glycol or polyethylene glycol.
 4. The filter according to claim 1, comprising the filter section (A) and/or filter section (B), and the filter section (C) on a downstream side of these filter sections.
 5. The filter according to claim 1, comprising a plain filter section at a most downstream position.
 6. A cigarette comprising a tobacco rod, and a filter according to claim 1, provided at one end of the tobacco rod. 